Spinal plate with screw locks and cam locks

Abstract

A bone plate for stabilizing adjacent vertebrae or ends of a bone having a span for extending across the discontinuity. The span has brackets for attaching to the bone. The brackets have countersunk apertures terminating through which bone screws are placed in the bone. An cam bore is located between the countersunk apertures and a cam with lobe surfaces is positioned in the cam bore. Upon rotation of the cam, the lobe surfaces engage an end of the wedge shoes and move them so that the other end of the wedge shoes move into the countersunk apertures and frictionally engage the heads of the bone screws. The wedge shoe is provided with means to lock the cam in position. The wedge shoe is also provided with means to indicate that the shoe has completely engaged the head of the bone screw in the countersunk aperture.

1. A bone fastener locking system for a bone plate comprising:
 a bone plate having at least two apertures each adapted for accepting a bone fastener, a substantially V-shaped channel extending between each of said at least two apertures, a rotatable cam positioned about an apex of said V-shaped channel, said cam being constructed and arranged to engage a free floating wedge shoe constrained by the inner surfaces in each leg of each of said V-shaped channel, said rotatable cam having a cam surface in contact with both of said wedge shoes, said cam rotatable to cause traversal of both of said wedge shoes along a respective leg of said V-shaped channel, said wedge shoes traversable between a disengaged position and an engaged position, whereby said disengaged position allows a bone fastener to be inserted into or removed from either of said respective at least two apertures and whereby said engaged position prevents substantial movement of a bone fastener placed in either of said respective at least two apertures. 
 
   
   
     2. The bone fastener locking system for a bone plate of  claim 1  wherein each said wedge shoe engages a side surface of a respective said bone fastener. 
   
   
     3. The bone fastener locking system for a bone plate of  claim 1  wherein said wedge shoes are enclosed within said bone plate. 
   
   
     4. A bone plate for attachment to bone across discontinuities comprising:
 an elongated span having a first end and a second end, a first bracket on said first end and a second bracket on said second end, said first bracket having at least two apertures adapted to receive bone fasteners, a substantially V-shaped channel extending between said at least two apertures, a rotatable cam positioned about an apex of said V-shaped channel, said cam being constructed and arranged to engage a free floating wedge shoe constrained by the inner surfaces in each leg of said V-shaped channel and said rotatable cam, said rotatable cam having a cam surface in contact with said wedge shoes, said cam rotatable to cause traversal of each of said wedge shoes along a respective leg of said V-shaped channel between a disengaged position and an engaged position, whereby said disengaged position allows a bone fastener to be inserted into or removed from either of said at least two apertures and whereby said engaged position prevents substantial movement of a bone fastener placed in either of said at least two apertures. 
 
   
   
     5. The bone plate of  claim 4  wherein said second bracket includes at least two apertures adapted to receive bone fasteners, a substantially V-shaped channel extending between said at least two apertures, a rotatable cam positioned at about an apex of said V-shaped channel, said cam being constructed and arranged to engage a free floating wedge shoe constrained by the inner surfaces in each leg of said V-shaped channel and said rotatable cam, said rotatable cam having a cam surface in contact with said wedge shoes, said cam rotatable to cause traversal of each said wedge shoe along a respective leg of said V-shaped channel between a disengaged position and an engaged position, whereby said disengaged position allows a bone fastener to be inserted into or removed from either of said at least two apertures and whereby said engaged position prevents substantial movement of a bone fastener placed in either of said at least two apertures. 
   
   
     6. A bone plate for attachment to bone across discontinuities comprising an elongated span having a first end and a second end, a first bracket on said first end and a second bracket on said second end, said first and said second bracket each having at least two apertures adapted to receive bone fasteners, said first bracket and said second bracket each having a substantially V-shaped channel therein extending between said at least two apertures, said channel including a plurality of internal surfaces, a rotatable cam positioned about an apex of said V-shaped channel, a free-floating wedge shoe disposed in each leg of said V-shaped channel, said rotatable cam having a cam surface in contact with each of said wedge shoes, each of said wedge shoes constrained by said plurality of internal channel surfaces and said cam surface, whereby rotation of said rotatable cam causes traversal of each of said wedge shoes along a respective leg of said V-shaped channel to prevent substantial bone fastener rotation. 
   
   
     7. The bone plate of  claim 6  comprising a countersunk bore surrounding at least one of said at least two apertures, said countersunk bore having a sidewall, said wedge shoe extending through a portion of said sidewall during rotation of said rotatable cam. 
   
   
     8. The bone plate of  claim 6  comprising a countersunk bore surrounding each of said at least two apertures, said bores each having sidewall, said wedge shoes extending through a portion of said sidewall during rotation of said rotatable cam. 
   
   
     9. The bone plate of  claim 6  wherein at least one of said wedge shoes is provided with a spring means to maintain said wedge shoe in contact with a head of a bone screw positioned in said aperture after said rotatable cam moves said wedge shoe into said aperture. 
   
   
     10. The bone plate of  claim 6  wherein each of said wedge shoes is provided with a spring means to maintain said shoes in contact with a head of a bone screw positioned in said aperture after said cam moves said shoes into said apertures. 
   
   
     11. The bone plate of  claim 6  wherein at least one of said wedge shoes is provided with an indicator which indicate that said wedge shoe has been slid sufficiently into said aperture to engage a head of a bone screw positioned in said aperture. 
   
   
     12. The bone plate of  claim 11  wherein the indicator comprises a groove on said at least one wedge shoe, said groove positioned on a surface of said at least one wedge shoe that is constrained by said rotatable cam. 
   
   
     13. The bone plate of  claim 6  wherein each of said wedge shoes is provided with an indicator which indicate that said wedge shoes have been slid sufficiently into said apertures to engage a head of a bone screw positioned in said aperture. 
   
   
     14. The bone plate of  claim 13  wherein the indicator comprises a groove on each of said at least two wedge shoes, said groove positioned on a surface of said at least one wedge shoe that is constrained by said rotatable cam. 
   
   
     15. The bone plate of  claim 6  wherein at least one of said wedge shoes includes an end constructed and arranged to engage a bone fastener positioned in said aperture. 
   
   
     16. The bone plate of  claim 15  wherein at least one of said wedge shoes includes an other end constructed and arranged to lock said rotatable cam in a position subsequent to a cam lobe surface engaging said wedge shoe. 
   
   
     17. The bone plate of  claim 6  wherein each of said at least two wedge shoes an end constructed and arranged to engage a bone fastener positioned in said aperture. 
   
   
     18. The bone plate of  claim 17  wherein each of said wedge shoes includes an other end constructed and arranged to lock said rotatable cam in a position subsequent to a cam lobe surface engaging said wedge shoes.